Improvement in pistons for printing-presses



l U51 CALVERT B. COTTRELL.

improvement in Pistons for Printing Presses.

No. 121,759. JMJ. Patented Dec. i2. mi.'

y f nvnuiur:

l .i NITED STATES PATENT OFFICE.

IMPROVEMENT IN PlSTONS FOR PRINTING-PRESSES.

Specication forming part of Letters Patent No. 121,759, dated December l2, 1871.

` To all whom it may concern:

Be it known that I, GALVERT B. Co'r'rRELL,

' of Westerly, in the county of Washington and State of Rhode Island, have invented a new and useful Improvement in Printing-Presses; and I do hereby declare that the following is a full, clear, and exact description thereof, which will l enable others skilled in the art to make and use l the same, reference being had to the accompanying drawing forming part of this speciiication.

My invention consists in improving the con- I struction of pistons which are reciprocated in cylinders and employed to form air-cushions to arrest, at each movement, the reciprocating table ot' a printing-press bed. The. object is to prevent l stoppage by a paper getting between the piston tion.

` line z z of Fig. 3; and Fig. 5 is a side elevation of the piston.

A represents the cylinders, and B the pistons employed in these presses to eiiect the stoppage of the table by the compression of the air in the cylinders behind the pistons. Heretofore the pistons have been solid, or, at least, so unyielding that the paper falling in front of a cylinder so as to be forced into it would pack so hard as to stop the press, requiring great force to release the piston, and sometimes breaking the cylinder and other parts. Now, I propose to construct these pistons with such capacity for yielding radially that the packing which Works against the wall of the cylinder will yield when any such matters are encountered by the piston so as not to obstruct the working of the press. This I propose to accomplish by a leather or other iexible packing, D, clamped between Wood or metal disks E F, which are considerably smaller than the cylinder, and shaped in cylindrical form in the part Dl which acts upon the cylinder, which part I stretch or adjust over a tlat coiled spring, G, or other equivalent support therefor arranged on the periphery ot' disk F, and sustained a considerable distance therefrom by the radial coiled springs H, or in any other Way, so that the said spring G, or other device or devices used instead, may have considerable movement radially when required. The coiled tlat spring (if may be sut'- ticiently strong to hold the elastic packing against the cylinder with sutlicient pressure Without the aid otl the springs H which will be needed more in case segmental plates or blocks of any kind be used instead of the spring G. The iiexible packing D will be contracted alittle at the side ofthe piston which enters the-cylinder first, as shown at K, to prevent catching on the rim of the cylinder, and the latter will be reamed ont, as at I, for the same object. In this example I have represented spring-pins L attached to the side ot' the piston for holding` the spri 1'1 gG from escaping' by their radial points passing through a tlange ot' the disk F and projecting in front ofthe edge ot' said springs. The pistons will be provided with a valve, M, to admit air behind them, when withdrawing, to supply the place of that escaping past the packing when the piston goes in, to prevent the action of a vacuum against the piston when withdrawing.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. A iiexible packing, D D', clamped between disks and expanded by a tlat spring, G, coiled around the disk F, as described, for the purpose set forth.

2. The tlexible packing D D', the iiat spring G, the spring-pins L, and the auxiliary springs H, all combined and applied together as and for the purpose set forth.

The above specification of my invention signed by me this 5th day of July, 1871.

CALVERT B. OOTTBELL.

T. B. MosHER. (117) 

